GE USM 36 Series Technical Reference And Operating Manual page 200

5 Operation
Change in the probe delay with DGS
Generally, a change in the probe delay automatically
also affects the shape of the sound field. This means
that a new recording of the reference echo for the DGS
setting would be theoretically required. However, minor
changes in the delay line, typically occurring due to the
wear of the delay line, have no noticeable effect on the
programmed distance laws.
A T T E N T I O N
An existing DGS setting no longer applies if
the probe delay changes to a larger extent,
e.g. caused by adding or removing a delay
line after recording a DGS reference echo
before changing the delay line.
The same applies to immersion testing: The
DGS setting must be made after setting up
the final water delay line.
Failure to do so may lead to evaluation er-
rors.
5-124
Automatic variation of the measuring point in TOF
mode
An echo amplitude evaluation is normally carried out at
the echo peak of the signal under examination because
this is the only way of ensuring that the displayed echo
amplitude and the sound path (projection distance,
depth position) always belong to the highest echo in the
gate.
N o t e
The USM 36 checks the measuring point set-
ting in TOF mode before processing any ref-
erence amplitudes. If PEAK is not set as
measuring point, the instrument will automat-
ically switch to PEAK. In this case, a note is
displayed at the bottom edge of the display
screen.
Issue 2 (12/2013)
Evaluation according to the DGS method
USM 36